Codoping approach is an appealing strategy to further improve the catalytic activity of Ce-based catalysts.In the present study,Mn and/or Cu doped ceria solid solutions MnxCuyCe1-x-yO2,CuxCe1-xO2,MnxCe1-xO2 and pure C...Codoping approach is an appealing strategy to further improve the catalytic activity of Ce-based catalysts.In the present study,Mn and/or Cu doped ceria solid solutions MnxCuyCe1-x-yO2,CuxCe1-xO2,MnxCe1-xO2 and pure CeO2 were prepared by CTAB-assisted hydrothermal method for CO oxidation.XRD,SEM,EDS,BET,Raman,H2-TPR,XPS and in situ DRIFTS techniques were carried out to study the physicochemical properties and to correlate them to the activity.The doped samples maintain the cubic fluorite structure of CeO2 with high crystallinity and small crystallite size,forming Ce-based solid solutions.The obtained catalysts have large mesoporous structure with average pore size of 10-14 nm.The doped transition metal enhances the oxygen vacancies and improves reducibility of the solids.The synergistic interaction of Mn and Cu codoping induces mo re oxygen vacancies,pro moting the increase of surface adsorbed oxygen and the transfer of bulk oxygen of catalyst,thereby enhancing the catalytic activity for CO oxidation.Besides,the decomposition rate of the carbonate species which is derived from in situ DRIFTS for each catalyst can provide a measure to evaluate its catalytic activity of CO oxidation.展开更多
In this work,a highly active CeO_(2) catalyst with hollow nanosphere morphology for low temperature NO_(x) storage was prepared by a surfactant-assisted solvothermal reaction.The physicochemical properties of ceria sa...In this work,a highly active CeO_(2) catalyst with hollow nanosphere morphology for low temperature NO_(x) storage was prepared by a surfactant-assisted solvothermal reaction.The physicochemical properties of ceria samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),N_(2) adsorption–desorption,H_(2)-temperature programmed reduction(H_(2)-TPR),X-ray photoelectron spectroscopy(XPS)and in situ diffused reflectance infrared Fourier transform spectroscopy(DRIFTS).The as-prepared CeO_(2) nanosphere possesses excellent NO oxidation capacity,smaller mesopores,better reducibility and more surface Ce^(3+)content.Compared with CeO_(2) with nanorod and nanoparticle morphologies,CeO_(2) nanosphere shows better intrinsic low temperature NO_(x) trapping performance,with a wide operating temperature window(150–300℃),high NO_(x) adsorption capacity(NAC,640–745μmol/g)and high NO_(x) storage capacity(NSC,250–350μmol/g).Two reaction pathways are speculated for NO_(x) adsorption on CeO_(2) nanosphere,including“nitrate route”and“nitrite route”.The thermally unstable surface nitrites formed on the CeO_(2) nanosphere allow ceria to release more NO_(x) during the desorption process.The present work provides a new ceria morphology for NO_(x) traps,which may become a potential excellent NO_(x) storage material.展开更多
Single-atom alloy catalysts represent a novel and advanced category of materials in heterogeneous catalysis,attracting considerable interest in electrochemical power storage and utilization because of the distinctive ...Single-atom alloy catalysts represent a novel and advanced category of materials in heterogeneous catalysis,attracting considerable interest in electrochemical power storage and utilization because of the distinctive structural attributes and remarkable catalytic capabilities.By establishing atomically precise arrangements of catalytic centers on metallic surfaces,single-atom alloy create highly efficient active sites with near-perfect atomic utilization.The robust electronic coupling and geometric interactions between the atomic-scale precision sites and the supporting metal matrix impart exceptional catalytic properties,such as improved kinetic performance,precise molecular recognition,and prolonged operational durability.In essence,the structural integrity of the isolated metal active sites in single-atom alloy,combined with their precisely tunable coordination environments,substantially boosts the electrochemical performance and catalytic efficiency.This review begins by introducing and discussing the fundamental concepts and inherent attributes of single-atom alloy.The methodological framework for single-atom alloy development was systematically examined,encompassing architectural design principles,fabrication methodologies,and analytical characterization techniques.Following this,the comprehensive summarization was conducted regarding the implementation of single-atom alloy catalysts in energy transformation technologies,with specific emphasis on fuel cells and environmentally electrochemical processes.Finally,forward-looking insights and perspectives are presented on the current challenges facing the development of single-atom alloy catalysts.展开更多
基金Project supported by the National Natural Science Foundation of China(21777055)Shandong Provincial Natural Science Foundation(ZR2017BB004)+1 种基金Shandong Province Key Research and Development Plan(2017GGX202004)Shandong Province Major Science and Technology Innovation Project(2017CXGC1004)
文摘Codoping approach is an appealing strategy to further improve the catalytic activity of Ce-based catalysts.In the present study,Mn and/or Cu doped ceria solid solutions MnxCuyCe1-x-yO2,CuxCe1-xO2,MnxCe1-xO2 and pure CeO2 were prepared by CTAB-assisted hydrothermal method for CO oxidation.XRD,SEM,EDS,BET,Raman,H2-TPR,XPS and in situ DRIFTS techniques were carried out to study the physicochemical properties and to correlate them to the activity.The doped samples maintain the cubic fluorite structure of CeO2 with high crystallinity and small crystallite size,forming Ce-based solid solutions.The obtained catalysts have large mesoporous structure with average pore size of 10-14 nm.The doped transition metal enhances the oxygen vacancies and improves reducibility of the solids.The synergistic interaction of Mn and Cu codoping induces mo re oxygen vacancies,pro moting the increase of surface adsorbed oxygen and the transfer of bulk oxygen of catalyst,thereby enhancing the catalytic activity for CO oxidation.Besides,the decomposition rate of the carbonate species which is derived from in situ DRIFTS for each catalyst can provide a measure to evaluate its catalytic activity of CO oxidation.
基金Project supported by the National Natural Science Foundation of China(21777055)Shandong Province Key Research and Development Plan(2019GSF109116,2018GGX102032)Natural Science Foundation of Shandong Province(ZR2020MB120,ZR2018LB026)。
文摘In this work,a highly active CeO_(2) catalyst with hollow nanosphere morphology for low temperature NO_(x) storage was prepared by a surfactant-assisted solvothermal reaction.The physicochemical properties of ceria samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),N_(2) adsorption–desorption,H_(2)-temperature programmed reduction(H_(2)-TPR),X-ray photoelectron spectroscopy(XPS)and in situ diffused reflectance infrared Fourier transform spectroscopy(DRIFTS).The as-prepared CeO_(2) nanosphere possesses excellent NO oxidation capacity,smaller mesopores,better reducibility and more surface Ce^(3+)content.Compared with CeO_(2) with nanorod and nanoparticle morphologies,CeO_(2) nanosphere shows better intrinsic low temperature NO_(x) trapping performance,with a wide operating temperature window(150–300℃),high NO_(x) adsorption capacity(NAC,640–745μmol/g)and high NO_(x) storage capacity(NSC,250–350μmol/g).Two reaction pathways are speculated for NO_(x) adsorption on CeO_(2) nanosphere,including“nitrate route”and“nitrite route”.The thermally unstable surface nitrites formed on the CeO_(2) nanosphere allow ceria to release more NO_(x) during the desorption process.The present work provides a new ceria morphology for NO_(x) traps,which may become a potential excellent NO_(x) storage material.
基金supported by the National Natural Science Foundation of China(Grant No.22208322)the Natural Science Foundation of Henan,China(Grant No.242300421230)the fund from the State Key Laboratory of Powder Metallurgy,China(Grant No.Sklpm-KF-021).
文摘Single-atom alloy catalysts represent a novel and advanced category of materials in heterogeneous catalysis,attracting considerable interest in electrochemical power storage and utilization because of the distinctive structural attributes and remarkable catalytic capabilities.By establishing atomically precise arrangements of catalytic centers on metallic surfaces,single-atom alloy create highly efficient active sites with near-perfect atomic utilization.The robust electronic coupling and geometric interactions between the atomic-scale precision sites and the supporting metal matrix impart exceptional catalytic properties,such as improved kinetic performance,precise molecular recognition,and prolonged operational durability.In essence,the structural integrity of the isolated metal active sites in single-atom alloy,combined with their precisely tunable coordination environments,substantially boosts the electrochemical performance and catalytic efficiency.This review begins by introducing and discussing the fundamental concepts and inherent attributes of single-atom alloy.The methodological framework for single-atom alloy development was systematically examined,encompassing architectural design principles,fabrication methodologies,and analytical characterization techniques.Following this,the comprehensive summarization was conducted regarding the implementation of single-atom alloy catalysts in energy transformation technologies,with specific emphasis on fuel cells and environmentally electrochemical processes.Finally,forward-looking insights and perspectives are presented on the current challenges facing the development of single-atom alloy catalysts.
